1. Field of the Invention
The present invention relates to processing apparatus for solid urban trash or refuse, and more specifically to processing apparatus which is capable of cutting or tearing solid refuse, especially plastic or plasticized bags containing the solid refuse, preliminarily to sorting of the solid refuse for recycling purposes.
2. The Prior Art
Over the past few years the popularity in urban areas of storing trash and solid domestic refuse in plastic or plasticized bags has increased drammatically. These bags, which may be in each case more or less filled with the solid domestic refuse, are conventionally left outside dwellings for pickup by public or private trash collectors, and these trash collectors will place the bags in their trucks and ultimately transport them to recycling plants for processing, sorting and recycling treatments.
Once at the recycling plant the bags containing the solid refuse must be broken open and their contents sorted, i.e., because the contents will include many different types of materials, e.g., smaller bags, boxes, cans, etc., which must be treated differently during recycling. Actually, automatic systems for opening bags containing solid refuse are difficult to construct, principally because any apparatus must accomodate for vast differences in shapes and hardnesses of materials which can be anticipated to be contained in the bags.
One apparatus for processing bags containing solid urban refuse is shown in U.S. Pat. No. 3,891,105. In this apparatus a series of spikes is used to hold each bag, these spikes cooperating with corresponding blades to provide a series of longitudinal tears or cuts in the treated material. However, the alternating motion utilized in this device limits the range of movement of the elements and thus a complete opening (cutting) is never obtained. This produces problems in the subsequent shearing operation because material is still left untouched in sections of the bags. In addition, this device fails to operate in a satisfactory way because there are two groups of blades and counteractive blades operating independently, the counteractive blades holding the refuse material to be sheared in a fixed position while the blades advance in the same direction and more quickly than the underlying conveyor, thus dragging the refuse material against the counteractive blades, each of which makes a tear, the counteractive blades being somewhat free in the cutting operation and the blades in the return mode. Moreover, the counteractive blades are in positive control only during the lift operation and their weight is what makes them operate in the lowering phase, while the blades are in a positive control during both operations. This device has thus proved to be overly permissive--the counteractive blades may easily retract when meeting objects having a certain resistance. The result is an irregular operation and frequent stoppages of operation of the apparatus.
Another known apparatus involves a high speed mill using fixed or articulated hammers or flexible whips attached to high speed rotors which are kept taut by centrifugal forces. However, this apparatus is not entirely desirable because it operates on the materials so vigorously that subsequent recovery of the cut materials into the desired categories is very difficult.
The present invention is directed to a process and apparatus which will operate to break open the bags containing the solid urban refuse and will also operate to compact and shear or cut the contained refuse, e.g., the boxes, plastic items, wood items, etc., which may be contained therein, so that the solid refuse can then be easily sorted out into the desired categories and further processed as necessary.